function settime(obj) { 
    if (countdown == 0) { 
        obj.prop('disabled',false);    
        obj.val('提交'); 
        countdown = 60; 
        return;
    } else { 
        obj.prop('disabled',true);
        obj.val("重新发送(" + countdown + ")"); 
        countdown--; 
    }
}
 //var countdown=60;